05000277/LER-1979-011-01, /01T-0 on 790302:engineering Review Determined Certain Containment Isolation Valves Incapable of Closing Against LOCA Pressure.Caused by Design Oversight.Future Mod to Expand Valve Open Alarm to Include Seal Low Pressure

/01T-0 on 790302:engineering Review Determined Certain Containment Isolation Valves Incapable of Closing Against LOCA Pressure.Caused by Design Oversight.Future Mod to Expand Valve Open Alarm to Include Seal Low Pressure

ML19289F311
Person / Time
Site:	Peach Bottom
Issue date:	03/29/1979
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19289F307	List: 05000277/LER-1979-011, Forwards LER 79-011/01T-0 05000277/LER-1979-011-01, /01T-0 on 790302:engineering Review Determined Certain Containment Isolation Valves Incapable of Closing Against LOCA Pressure.Caused by Design Oversight.Future Mod to Expand Valve Open Alarm to Include Seal Low Pressure
References
LER-79-011-01T-01, LER-79-11-1T-1, NUDOCS 7906070215
Download: ML19289F311 (1)

LER-1979-011, /01T-0 on 790302:engineering Review Determined Certain Containment Isolation Valves Incapable of Closing Against LOCA Pressure.Caused by Design Oversight.Future Mod to Expand Valve Open Alarm to Include Seal Low Pressure

Event date:
Report date:
2771979011R01 - NRC Website

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CONTROL BLOCK: l l

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l l lh (PLE ASE PRINT OR TYPE ALL REQUIRED INFoRMATION.

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, LICENSEE CODE 14 LICENSE NUM8tR 2b 26 LICENSE TYPt JO

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2 1 Engineering review determined certMn containment isolation valves in-_

,j F6T3-l l capable of closing against LOCA pressure. Analysis showed the valves will.

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@l close if restricted to 37 degrees open.Further investigation and inspec,

,J Ql tion determined valve seal control system not seismically certified. 3 l

o a i valve seals found uninflated. Valves normally closed during opar.LOCA, o

7 l seismic event,and failure of control system on redundant valves would be

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gl required before event would have significant safety implications.,_

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS i

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Cause-design oversight-at discovery of inability to close, valves blocked

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,y closed-opening under sta. supt. authorization limited to 30 degrees.Upon,

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2 I seismic concern, seismically designed control system installed.3uninflat-i i

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ed seals caused by linkage misadjust=ent-readjusted. Future modification j

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I expands existing " Valve open" alsrm to include seal low pressure.

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